Keep an excluded contact out of the score the way N1MM does

Three things were wrong with a contact the operator takes out of the claimed
score. The decompiled reference gives the rule in four places:

- `Contest.cs:437` returns zero points when `IsClaimedQso` is 0.
- `ContestInstance.cs:307` builds the where clause `CLAIMEDQSO = 1`, which the
  dupe search (`DBSupport.cs:1189`) and the multiplier search
  (`DBSupport.cs:1327`) both use, so an unclaimed contact takes nothing away
  from a later one.
- The score query (`DBSupport.cs:1807`) adds `ContactType <> 'D'`, which the
  other two do not. A contact marked as a dupe is therefore still searched for
  dupes and multipliers, and is left out of the score alone.
- `Contact.cs:1563`, `3307` and `3881` write `X-QSO:` rather than dropping the
  contact from the Cabrillo file.

`ContestLog` scored an unclaimed contact in full, and the Cabrillo writer left
it out of the file. `Qso.IsInScore` now holds the score rule and
`StatisticsPivot` uses it instead of its own copy.

The same reference also fixes the sent serial in three Cabrillo exporters.
ARRL 10M, Ukrainian DX and YO DX HF formatted the sent exchange from the
station rather than the contact, so a DX entrant exported `001` on every line.
N1MM reads the contact's own number: `CArrl10m.cs:122` writes it unpadded,
`CUkrainian.cs:232` and `CYOHFDX.cs:167` pad it to three digits.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015NZkFxHde1iifAQemFTHxf

tests/Nonemm.Formats.Tests/CabrilloWriterTests.cs

@@ -73,14 +73,36 @@ public class CabrilloWriterTests
         Assert.EndsWith("END-OF-LOG:\r\n", log);
     }
 
+    /// N1MM writes a contact the operator left out of the claimed score under
+    /// `X-QSO:`, which the sponsors read as a contact the entrant is not
+    /// claiming. It is not dropped from the file.
     [Fact]
-    public void ContactsLeftOutOfTheClaimedScoreAreNotSent()
+    public void ContactsLeftOutOfTheClaimedScoreAreSentAsXQso()
     {
         CabrilloWriter writer = new(new CqWorldWide(ModeCategory.Cw), Me);
         string log = writer.Write(
             new CabrilloHeader { Contest = "CQ-WW-CW", Callsign = "DL1ABC" },
             [Contact() with { IsClaimed = false }]);
-        Assert.DoesNotContain("QSO:", log);
+        Assert.Contains("\r\nX-QSO: ", log);
+        Assert.DoesNotContain("\r\nQSO: ", log);
+    }
+
+    /// The three contests where a DX entrant sends a serial. N1MM writes the
+    /// serial of that contact, so a log cannot come out with `001` on every
+    /// line. ARRL 10M sends it unpadded, the other two pad it to three digits.
+    [Fact]
+    public void ADxEntrantSendsTheSerialOfTheContact()
+    {
+        Qso qso = Contact(28_025) with { SentNumber = 42 };
+        Assert.Contains(
+            "599 42     JA1XYZ",
+            new CabrilloWriter(new Arrl10Metre(), Me).QsoLine(qso));
+        Assert.Contains(
+            "599 042    JA1XYZ",
+            new CabrilloWriter(new UkrainianDx(), Me).QsoLine(qso));
+        Assert.Contains(
+            "599 042    JA1XYZ",
+            new CabrilloWriter(new YoDxHf(), Me).QsoLine(qso));
     }
 
     /// The SA 10 file, whose sponsor asks for its own columns: the operator's